A. Field of the Invention
The present invention relates to an endoscope in which a moving part of its insertion section is driven by means of a motor which utilizes the vibration of a vibrator for rotation.
B. Description of the Related Art
Disclosed in Japanese Patent Disclosure No. 61-106126 is an endoscope in which a moving part, e.g., a bending portion, of its insertion section is bent by means of a motor which rotates by utilizing the vibration of a vibrator. The vibrating-type motor of this endoscope comprises a rotor, a stator, and an urging member for bringing the stator into intimate contact with the rotor. The rotor is connected to one end of an operating wire, the other end of which is coupled to the bending portion of the insertion section. As a vibration is produced between the rotor and the stator, the rotor is rotated by the agency of progressive waves, whereby the bending portion is bent by means of the operating wire.
In the conventional endoscope using the vibrating-type motor, when the motor is energized, the rotor, and hence, the bending portion connected thereto, can be freed by producing standing waves between the rotor and the stator. In case of power failure, however, the rotor and the stator will be pressed against the urging member, and fixed by means of frictional force between themselves. As a result, the bending portion will be locked.
If a control circuit for driving the vibrating-type motor goes wrong, moreover, the bending portion of the insertion section will not be able to be freed.